<title>RoBlock: a prototype autonomous manufacturing cell</title>

Abstract

RoBlock is the first phase of an internally financed project at the Institute aimed at building a system in which two industrial robots suspended from a gantry, as shown below, cooperate to perform a task specified by an external user, in this case, assembling an unstructured collection of coloured wooden blocks into a specified 3-dimensional pattern. The blocks are indentified and localised using computer vision and grasped with a suction cup mechanism. Future phases of the project will involve other processes such as grasping and lifting, as well as other types of robot such as autonomous vehicles or variable geometry trusses. Innovative features of the control software system include: ○ The use of an advanced trajectory planning system which ensures collision avoidance based on a generalisation of the method of artificial potential fields [1], ○ The use of a generic model-based controller which learns the values of parameters, including static and kinetic friction, of a detailed mechanical model of itself by comparing actual with planned movements [2], ○ The use of fast, flexible, and robust pattern recognition and 3D-interpretation strategies, ○ Integration of trajectory planning and control with the sensor systems in a distributed Java application running on a network of PC's attached to the individual physical components. In designing this first stage, the aim was to build in the minimum complexity necessary to make the system non-trivially autonomous and to minimize the technological risks. The aims of this project, which is planned to be operational during 2000, are as follows: ○ To provide a platform for carrying out experimental research in multi-agent systems and autonomous manufacturing systems, ○ To test the interdisciplinary cooperation architecture of the Maersk Institute, in which researchers in the fields of applied mathematics (modelling the physical world), software engineering (modelling the system) and sensor/actuator technology (relating the virtual and real worlds) could collaborate with systems integrators to construct intelligent, autonomous systems ○ To provide a showpiece demonstrator in the entrance hall of the Institute's new building. 1. CONSUMER-DRIVEN MANUFACTURING Intelligent Manufacturing Systems (IMS) address the needs of today's rapidly changing, consumer-driven market, where the demands of customers are moving towards more variants of models, and thus shorter production runs [3], which, based on research at Daimler-Chrysler, argues that conventional manufacturing control systems are not suited to handle this task, because such systems are either too difficult or too expensive to modify. This inflexibility is due to both product-specific control software and statically configured manufacturing equipment. This severely limits the generality and reusability of manufacturing systems even though they may be composed of highly flexible, reusable components such as industrial robots and machine tools. Until recently, such systems have been economic because they are optimal with respect to setup cost and project implementation-run cycles. This minimisation of the initial work load is achieved at the cost of much higher subsequent costs of modifying the system. This makes the idea of flexible, automatic production very attractive to forward-looking manufacturing companies.